In some circumstances it may be appropriate or necessary to improve the fit of a pneumatic tire on a wheel such as a motor vehicle wheel, for example in a tire fitting apparatus and in particular in an automatic tire fitting assembly line. A typical form of apparatus for improving the fit of a pneumatic tire on a disc wheel, as is to be found in DE 38 23 721 A1, comprises a plurality of pressure rollers which are disposed in such a way that in use they are arranged around the periphery of the tire, and they can be pressed by means of inclined peripheral surfaces against the tire. The pressure rollers, being generally therefore of a conical configuration, are all arranged in such a way that they produce a downwardly directed force component which urges the wheel or the tire towards support rollers on which it is mounted. The degree of conicity of the pressure rollers is small in that apparatus so that the main force component exerted by the pressure rollers is directed generally radially inwardly against the tire in order thereby to ensure that the tire bead is correctly seated on the flange portion of the rim of the disc wheel. If however the apparatus produces an excessively inclined, downwardly directed force component, there is the danger of the tire being loaded thereby at only one side, which will accordingly result in the tire being seated in different ways at the two side flanges of the rim of the disc wheel. For example, in such a situation, it may happen that the fit of the tire at the upper flange portion of the wheel rim is improved while the seating of the tire at the other flange portion of the wheel rim may be made worse.